The present invention relates to satellite communication systems employing mobile or hand-held communication devices such as Inmarsat-P, Iridium, Globalstar, and Odyssey. In these systems, there is a need to transmit signals to a hand-held communication device on a regular basis for signaling, synchronization, paging, and short message delivery.
One constraint placed on satellite communication with hand-held communication devices is the fact that they must be turned on in order to receive any messages.
Each hand-held communication device should have a sleep/wake cycle with short wake intervals between is long sleep intervals so that the duty factor is kept small in order to conserve battery power. To this end, hand-held communication devices are divided into subgroups with each device being assigned to only one subgroup. The duty factor is kept small if a large number of subgroups are employed and the hand-held communication devices belonging to each subgroup wake at only specified intervals.
One problem with the conventional method in which each hand-held communication device is assigned to only one subgroup is that the queuing delay caused by statistical fluctuations in the traffic to the different subgroups increases as the number of subgroups increases. Thus, with the conventional method of assigning hand-held communication devices, the queuing delay corresponding to a given throughput can be great when a large number of subgroups are employed in a satellite communication system.